This invention relates to torque-transmitting mechanisms and, more particularly, to hydraulically actuated torque-transmitting mechanisms having at least one spring for returning the piston to a disengaged condition.
Torque-transmitting mechanisms are used in automatic shifting power transmissions to effect ratio changes within the planetary gearing of the transmission. The torque-transmitting mechanisms generally include two housings, which are splined therewith friction discs or plates, which are interdigitated, such that upon engagement of the discs, torque is transmitted between the two housings. The friction discs or plates are actuated into a frictional torque transmitting arrangement and engagement by a fluid activated piston, which moves axially within a cylinder, which might be incorporated within one of the housings.
The piston is disengaged when the pressure in the apply chamber is reduced to a minimum number or value so that the piston can be returned from the engaged position to a disengaged position thereby permitting the friction discs to rotate relative to each other with their respective housings. The piston is urged out of engagement with the friction discs by at least one spring member, which usually either a Belleville spring or a coil spring assembly having a plurality of coil springs which are held in a single assembly within the torque transmitting mechanism.
The return spring means, as they are often termed, require axial space within the transmission and therefore add to the overall axial limit of the transmission in many instances. In current or modern day transmissions, the axial length of the transmission is becoming more and more important, particularly transverse-mounted transmissions in many front-wheel drive vehicles. Also, the shorter axial length transmissions reduce the intrusion into the operator cockpit on rear-wheel drive vehicles. This will, of course, reduce the well-known center hump in many of today""s vehicles.
It is an object of the present invention to provide an improved torque-transmitting mechanism for a power transmission.
In one aspect of the present invention, the torque-transmitting mechanism incorporates a hydraulically actuated apply piston and a return spring mechanism.
In another aspect of the present invention, the return spring mechanism is an integral component of the apply piston.
In yet another aspect of the present invention, the apply piston and return spring provide at least one sidewall for an apply chamber for the torque-transmitting mechanism.